Automating chemical analyses is a desirable objective in a number of situations. For example, in the clinic or hospital setting, a large number of patient blood or urine samples need to be analyzed on a daily basis for a wide variety of different antigens or analytes. Highly advanced systems have been developed for analyzing these types of samples, and for allowing different tests to be performed on different samples as well as for recording test results for subsequent use in, for example, patient assessment and care. Exemplary systems are described in U.S. Pat. Nos. 6,027,691; 5,902,548; 5,885,530; 5,885,529; 5,807,523; 5,723,092; 5,721,141; 5,632,399; 5,620,898; 5,318,748; 5,316,726; 5,258,309; 5,098,845; 5,084,240; 5,008,082 and 4,639,242 all of which are herein incorporated by reference. As another example, automated systems may be used for detecting contaminants in water sources, food products, etc.
Despite the advanced systems for automated chemical analysis, there remains a need for improving the level of automation, the mechanisms which allow random access to and testing of samples, and the speed in processing large numbers of samples (i.e., throughput). Presently, the current automated technologies either involve carousels, which allow large numbers of samples or agents to be present and easily accessible, or linear racks and conveyers where the materials stored in the racks are easily presented for operations in a sequential manner. While the carousel systems have the advantage of easy access to large numbers of samples, the prior art systems suffer from having to empty the carousels in a batch like process in order to handle new samples. Conversely, while the linear rack based systems allow for easy automation, it is generally more difficult to retrieve a sample at different times to perform different tests.